This is an investigator initiated, NHLBI-funded, five year study, involving 140 white and black families and about 600 individuals, 200 of whom were recruited and trained at the University of Minnesota's Laboratory of Physiological Hygiene and Exercise Science. Recruitment and exercise training were completed by December, 1996. Three years of additional NIHLBI-funding has been obtained for data analysis and manuscript preparation. The purpose of the study is to evaluate the effects of 20 weeks of exercise training in the laboratory on physical fitness and risk factors for CVD and NIDDM and to determine the contribution of genetics to variability in responsiveness.